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Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"

442

SPERMACETI OIL

The purity of a spermaceti is judged from its melting point, acid and
saponification numbers and the amount of unsaponifiable matter (see General
Methods, 4, 7, 8 and 19). Addition of stearine or wax gives an acid number,
while that of tallow or other fat increases the saponification number ; solid
paraffin or ceresine lowers the saponification number and increases the
amount of unsaponifiable matter.

The two following tests are prescribed by the Official Italian Pharma-
copoeia :

1.  SOLUBILITY IN BENZENE.    I gram of the spermaceti is  dissolved
in 3 grams of benzene at a gentle heat : on cooling the liquid should remain
clear.

2.  TEST FOR'STEARIC ACID,    i gram  is  boiled  with  50 c.c. of 90%
alcohol and i gram of dry sodium carbonate, and filtered :   the filtrate,
when acidified with a dilute acid, should become barely opalescent, any
precipitate indicating the presence of stearic acid.

*
* *

According to the Official Italian Pharmacopoeia, pure spermaceti should
have no odour of fish, should have a specific gravity 0-940-0-950, and should
melt at 50-54 or, if recrystallised from alcohol, at 54-55 ; the alcoholic solu-
tion should not have an acid reaction ; tests i and 2 should be fulfilled.

SPERMACETI   OIL

This is the liquid part of the oil contained in the cephalic cavity of the
cachalot and allied species.

The ordinary refined spermaceti oil of commerce is an almcst colourless
or pale yellow liquid, mobile and nearly odourless.

It is a liquid wax, consisting mostly of esters of one or more higher
alcohols with fatty acids of the oleic acid series (fisetoleic acid). It con-
tains 37-45% of higher alcohols (unsaponifiable substances) and about 60%
of fatty acids combined with these alcohols ; it contains also very small
quantities (c -1-0-4%) of free acids and it turns rancid with great difficulty.
Its characters are shown in Table XLIX.

Detection of Adulterations.  Adulteration with mineral oils or fatty
oils is common. These may be detected by determining the specific gravity,
saponification and iodine numbers, and unsaponifiable substances, bearing
in mind the following :

1.  MINERAL OILS.   These lower the saponification number and increase
the content in unsaponifiable substances.    If the latter are boiled with
acetic anhydride and then cooled, the mineral oils separate almost com-
pletely from the liquid (see General Methods, 19).

2.  FATTY OILS.   These raise the specific gravity and the saponification
number and diminish the proportion of uiisaponifiable substances.    They
may be recognised by the presence of glycerine as indicated under Beeswax,
10.      44-46   i   5-13    i 75-145